Dynamic adjustment of downlink/uplink allocation ratio in TDD wireless systems

ABSTRACT

Techniques, apparatuses, and systems for dynamically changing downlink and uplink allocations can include operating a base station under time division duplexing to communicate with one or more mobile devices using a frame structure, adjusting a downlink-uplink ratio to change an allocation between uplink and downlink data capacities in the frame structure, determining a mute interval based on the adjusted downlink-uplink ratio, generating mute information based on the mute interval to identify the one or more areas of the frame structure effected by the allocation change, and transmitting the mute information to the one or more mobile devices.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of the priority of U.S. ProvisionalApplication Ser. No. 61/027,412, filed Feb. 8, 2008 and entitled“Dynamic Adjustment of Downlink/Uplink Allocation Ratio in TDD WirelessSystems,” the entire contents of which are hereby incorporated byreference.

BACKGROUND

This application relates to wireless communications.

Wireless communication systems such as a wireless Time Division Duplex(TDD) systems can include a network of one or more base stations tocommunicate with mobile devices such as user equipment (UE), mobilestation (MS), cell phone, or wireless air card. Further, a wirelesscommunication system can include a core network to control the basestations.

Wireless TDD systems can support downlink and uplink transmissions onthe same carrier frequency in separate non-overlapping time intervals. Abase station can transmits a signal, called a downlink signal, to one ormore mobile devices. A mobile device can transmit a signal, called anuplink signal, to one or more base stations. A wireless system canallocate downlink and uplink intervals to control downlink and uplinktransmissions in a frame.

SUMMARY

This patent application describes technologies that, among other things,dynamically change downlink and uplink allocations for wirelesscommunications.

Techniques for changing dynamically changing downlink and uplinkallocations can include establishing a communication link between a basestation and a user equipment (the communication link can includedownlink intervals for the base station to transmit to the userequipment and uplink intervals for the user equipment to transmit to thebase station); and generating a mute interval to replace a downlinkinterval or an uplink interval in a previous frame to effect a change ina downlink-uplink allocation ratio for a subsequent frame; andtransmitting a location of the mute interval to the user equipment usinga frame structure. Other implementations can include correspondingsystems, apparatus, and computer program products.

Techniques for dynamically changing downlink and uplink allocations caninclude operating a base station under time division duplexing tocommunicate with one or more mobile devices using a frame structure,adjusting a downlink-uplink ratio to change an allocation between uplinkand downlink data capacities in the frame structure, determining a muteinterval based on the adjusted downlink-uplink ratio, generating muteinformation based on the mute interval to identify the one or more areasof the frame structure effected by the allocation change, andtransmitting the mute information to the one or more mobile devices.Other implementations can include corresponding systems, apparatus, andcomputer program products.

Techniques can include using time division duplexing to communicate witha base station using a frame structure and a first allocation, receivingmuting information from the base station indicative of muting activityfor a specific area of the frame structure, and indicative of a secondallocation that differs from the first allocation, completing operationsassociated with the specific area under the first allocation; andcommencing operations using the second allocation. The frame structurecan include uplink and downlink data areas. The first allocation caninclude a total size of the uplink area and a total size of the downlinkarea. Other implementations can include corresponding systems,apparatus, and computer program products.

An apparatus can include a transceiver to communicate with one or moremobile devices using a frame structure under time division duplexing anda processing unit, in communication with the transceiver, configured toperform operations including adjusting a downlink-uplink ratio to changean allocation between uplink and downlink data capacities in the framestructure; determining a mute interval based on the adjusteddownlink-uplink ratio, the mute interval can include one or more areasof the frame structure; generating mute information based on the muteinterval to identify the one or more areas of the frame structureeffected by the allocation change; and transmitting the mute informationto the one or more mobile devices.

An apparatus can include a transceiver to communicate with a basestation; and a processing unit, in communication with the transceiver,configured to perform operations including using time division duplexingto communicate with the base station using a frame structure and a firstallocation, receiving muting information from the base stationindicative of muting activity for a specific area of the framestructure, and indicative of a second allocation that differs from thefirst allocation, completing operations associated with the specificarea under the first allocation; and commencing operations using thesecond allocation. The frame structure can include uplink and downlinkdata areas. The first allocation can include a total size of the uplinkarea and a total size of the downlink area.

A system for wireless communications can include a controller and one ormore base stations. A controller can perform operations includingadjusting a downlink-uplink ratio to change an allocation between uplinkand downlink data capacities in a frame structure; determining a muteinterval based on the adjusted downlink-uplink ratio, the mute intervalcan include one or more areas of the frame structure; generating muteinformation based on the mute interval to identify the one or more areasof the frame structure effected by the allocation change. A basestation, in communication with the controller, can communicate with oneor more mobile devices using the frame structure under time divisionduplexing and can transmit data including the mute information to theone or more mobile devices.

Particular implementations of the subject matter described in thispatent application can be implemented to realize one or more of thefollowing potential advantages. Dynamically changing adownlink-to-uplink (D/U) resource allocation ratio can increasebandwidth efficiency. Additionally, these advantages can includeavoiding a synchronized operations between base stations when changing aD/U ratio, e.g., avoiding a synchronized shut-down when changing a D/Uratio; and allowing, either temporarily or permanently, more than onedifferent D/U ratio in a wireless communication system with multiplebase stations. Further, these advantages can include minimizing oreliminating a system capacity loss during a D/U ratio change,elimination of an interrupt frame from a network view-point, and/orun-interrupted user traffic.

The details of multiple implementations are set forth in theaccompanying drawings and the description below.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an example of a slot based frame structure.

FIG. 2 shows an example of a guard slot structure.

FIG. 3 shows an example of a symbol based frame structure.

FIG. 4 shows an example of mute slot signaling using a slot mask.

FIG. 5 shows an example of mute slot signaling using a slot list.

FIG. 6 shows an example of mute symbol signaling using a symbol set.

FIGS. 7A,7B show different examples of processing mute intervals in abase station.

FIGS. 8A,8B show different examples of processing mute intervals in amobile device.

FIGS. 9A,9B show different examples of network flow for mute and muterecover functions.

FIG. 10 shows an example of a single step change in a multiple step D/Uratio adjustment for a slot based frame structure.

FIG. 11 shows an example of a single step change in a multiple step D/Uratio adjustment for a symbol based frame structure.

FIG. 12 shows an example of a multi-tier layout map with different D/Uallocation ratios.

FIG. 13 shows an example of a K-tier D/U ratio adjustment algorithm fora slot based frame structure.

FIG. 14 shows an example of a K-tier D/U ratio adjustment algorithm fora slot based frame structure.

FIG. 15 shows an example of a wireless communication system.

FIG. 16 shows an example of a radio station architecture.

FIG. 17A,17B show different examples of mute operation processes on abase station.

FIG. 18 shows an example process of a mute operation on a mobile device.

Like reference symbols in the various drawings indicate like elements.

DETAILED DESCRIPTION

Wireless TDD systems can use a frame structure to control downlink anduplink transmissions in TDD frame based communications. A framestructure can specify locations or intervals within a frame for downlinkand uplink transmissions and guard periods. When switching betweendownlink and uplink transmissions, TDD communications can use a guardperiod (GP). In some implementations, base stations and mobile devicesmay not transmit in a GP. Due to characteristics of some wirelesssystems such as cellular, switching from a downlink signal to an uplinksignal may require a longer GP, while switching from an uplink signal toa downlink signal may require a relatively shorter GP. A wireless TDDsystem can combine a TDD technique with a multiple access technologysuch as Code Division Multiple Access (CDMA) or OrthogonalFrequency-Division Multiplexing (OFDM).

Advantages of a TDD system can include the flexibility of bandwidthallocation in an unpaired frequency band, and the flexibility inselecting a downlink-to-uplink resource allocation ratio (D/U ratio).Different traffic service types and changing traffic flows can promptchanges to a D/U ratio.

However, TDD systems requiring a uniform and static D/U ratio may not beable to adapt to different traffic service types, changing trafficflows, or different downlink/uplink usages in different service areas.For example, some implementations of a TDD system require system-widesynchronization of a D/U ratio, e.g., when a base station transmits on adownlink, a mobile device does not transmit but receives signals, andwhen the mobile device transmits on the uplink, the base station turnsoff the base station's transmitter and receives signals. Further, insome TDD implementations, base stations and mobile devices can transmitand receive according to a system wide timing schedule in order to avoidoverlaps between downlink and uplink signals in the system.

Some TDD system implementations may be encumbered by having D/U ratiosynchronization across a system's base stations and mobile devicesbecause there can be only one D/U ratio per carrier frequencysystem-wide in such systems. Further, once a D/U ratio is determined forsuch a system, it may be difficult and time consuming to change the D/Uratio to other values. For example, before changing a D/U ratio in asynchronized fashion, each transmitter has to first either turn off thetransmission all together, or, in order to keep the continuity ofunfinished traffic, gradually reduces its own transmission volume tozero and then possibly wait a long time for other transmitters tocompletely shut down. As a result, such systems may waste a large amountof system capacity. In addition to a loss of traffic volume, themonitoring and management of unfinished traffic in such a system may beexpensive and/or time consuming.

This application describes implementations of and examples fortransmission and reception of signals in a TDD system, where thedownlink and uplink wireless signals are transmitted on the same carrierfrequency but in different time durations. The TDD system can beimplemented in a wireless environment. The examples and implementationsof wireless communication apparatus, techniques, and systems in thisapplication can dynamically change a downlink to uplink resourceallocation ratio in the time domain. These apparatus, techniques, andsystems can avoid a synchronized shut-down when changing thedownlink/uplink (D/U) ratio and can allow more than one different D/Uratio in the system, either temporarily or permanently.

In addition, these apparatus, techniques, and systems can be used invarious scenarios. These scenarios can include when a network needs toswitch from an old D/U allocation ratio to a new D/U allocation and whenthe network needs to keep the D/U allocation ratio of one service areadifferently from a D/U allocation ratio of a neighboring service area.

Different wireless TDD systems can use different types of framestructures to control downlink and uplink transmissions in TDD framebased communications. Examples of frame structure types include a slotbased frame structure, e.g., slot-TDD frame, and a symbol based framestructure, e.g., symbol-TDD frame.

FIG. 1 shows an example of a slot based frame structure. A slot basedframe structure such as a slot-TDD frame can include one or more ofdownlink slot, uplink slot, and guard slot. In some implementations, aslot based frame structure implementation can specify a fix-length radioframe and can include multiple slots. Each slot can potentially be usedfor a downlink transmission, an uplink transmission, or a guard periodfollowing a downlink slot and an leading uplink slot. A downlink slot oran uplink slot can include one or more data symbols and can have thesame slot length in time. Multiple mobile devices can share radioresources within a downlink slot or uplink slot. Components such as acore network or a scheduler located on a base station can control amultiple-access scheme including the scheduling of radio resources.Wireless systems such as 3GPP and 3GPP2 systems, e.g., TD-SCDMA,LTE-TDD, and UMB-TDD, can use a slot based frame structure.

FIG. 2 shows an example of a guard slot structure. A slot used for aguard period is called a guard slot. A guard slot can have a differentinterval from that of a uplink or downlink slot. In someimplementations, a guard slot's position within a frame is fixed. Aguard slot can include a guard period and one or more optional dataportions. In some implementations, a data portion proceeding a guardperiod is for a downlink signal, and a data portion following the guardperiod is for an uplink signal. The guard period when switching fromuplink to downlink can be relatively short. Some implementations cancreate a guard period by removing several last data symbols within theuplink slot that is prior to the downlink slot.

The number of downlink slots to the number of uplink slots in a framestructure is related to a D/U ratio. A base station can use one or moredownlink slots or can use a communication channel such as a broadcastchannel to communicate downlink and uplink slot assignments. A wirelesssystem can reserve downlink radio resources in a frame for broadcastingD/U allocation information.

FIG. 3 shows an example of a symbol based frame structure. A symbolbased frame structure such as a symbol-TDD frame structure can includeone or more of downlink symbol, uplink symbol, and guard period. In someimplementations, a symbol based frame structure implementation canspecify a fix-length radio frame and specifies a period for transmissionof downlink symbols, a guard period, and a period for transmission ofuplink symbols. Multiple mobile devices can share radio resources overdownlink symbols or uplink symbols. Components such as a core network ora scheduler located on a base station can control a multiple-accessscheme including the scheduling of radio resources. A guard period canhave a fixed time duration. The position of a guard period within aframe can depend on the number of downlink symbols preceding the guardperiod.

The number of downlink symbols to the number of uplink symbols in aframe structure is related to a D/U ratio. Accordingly, the position ofa guard period is also related to the D/U ratio. When switching fromuplink to downlink in a frame, some implementations can create a guardperiod by removing several last uplink symbols within the frame. A basestation can use one or more downlink symbols or can use a communicationchannel such as a broadcast channel to communicate the number ofdownlink/uplink symbols in a frame or the GP position in a frame. Awireless system can reserve downlink radio resources in a frame forbroadcasting D/U allocation information. Wireless systems such as IEEE802.16 (WiMAX) can use a symbol based frame structure.

Wireless communication systems can employ one or more mute intervals tosignal a D/U allocation change. A frame structure can include one ormore mute intervals in addition to downlink interval(s), uplinkinterval(s), and guard period(s). Different types of frame structureimplementations such as slot and symbol based frame structures can usemute intervals.

In a slot-TDD frame structure, a mute interval can include one or moreslots. A slot for a mute interval is known as a mute slot. A frame basedon a slot based frame structure can have one or more mute slots. In someimplementations, a mute slot is similar to the downlink and uplink slotsas shown in FIG. 1. Indicating a downlink slot or an uplink slot as amute slot can signal a change in D/U allocation. In someimplementations, once a downlink or uplink slot is marked as a muteslot, the slot can not be used for new user traffic transmission, untilthe slot is marked differently, e.g., marked as a downlink slot oruplink slot. Radio stations such as a base station or a mobile devicecan response to a mute slot, for example, by completing current traffictransmissions that utilize the mute slot or by stopping all existingtransmissions that utilize the mute slot immediately. A wireless systemcan transit a downlink slot to an uplink slot, or vice versa, by markingthe slot as a mute slot and waiting for all existing transmission withinthat slot to terminate.

A mute slot can differ from a guard slot. In some implementations, thetime duration of a mute slot is equal to that of a downlink/uplink slot,while a guard slot may not have such a requirement. In someimplementations, a mute slot shall have no new transmission signalduring the whole slot and the mute slot has its traffic volumedecreasing to zero, while a guard slot can have an optional data portionfor downlink and/or uplink transmission. In some implementations, a muteslot can be any downlink slot or an uplink slot within a framestructure, and a network can dynamically allocate and signal one or moreof the downlink and uplink slots as a mute slot(s), while a guard slotcan have a static position within a frame structure.

In a symbol-TDD frame structure, a mute interval can include one or moresymbols. A symbol for a mute interval is known as a mute symbol. A framebased on a symbol based frame structure can have one or more mutesymbols. In some implementations, a mute symbol is similar to downlinkand uplink symbol as shown in FIG. 3. In some implementations, once adownlink or uplink symbol is marked as mute symbol, the symbol can notbe used for new user traffic transmission, until the symbol is markeddifferently, e.g., marked as a downlink symbol or uplink symbol. Radiostations such as a base station or a mobile device can response to amute symbol, for example, by completing current traffic transmissionsthat utilize the mute symbol or by stopping all existing transmissionsthat utilize the mute symbol immediately. A wireless system can transita downlink symbol to an uplink symbol, or vice versa, by marking thesymbol as a mute symbol and waiting for all existing transmission withinthat symbol to terminate.

A mute symbol can differ from a guard period. In some implementations,the time duration of a mute symbol is equal to that of a downlink oruplink symbol, while a guard period has no such requirement. In someimplementations, a core network can explicitly signal the number andposition of the mute symbols within a frame structure, while the guardsymbol has a specific position within a radio frame implicitly derivedfrom the number of downlink symbols in the radio frame.

A wireless communication system can explicitly signal one or more muteintervals, e.g., signaling of mute slot(s) in a slot-TDD frame or mutesymbol(s) in symbol-TDD frame. Wireless systems such as a cellularsystem can require explicit signaling of mute intervals.

A base station, for example, can transmit common reference signals andcommon control information along with downlink user traffic on adownlink channel. A downlink scheduler on the base station side cancontrol the transmission of downlink user traffic. A wireless system maynot be able to turn off the transmission of common reference signals forsynchronization and tracking as well as the channel quality measurementperformed in user equipment. In some implementation, once a system plansto switch a specific downlink interval, e.g., slot or symbol, to anuplink interval, e.g., slot or symbol, the system can operate one ormore radio stations to cease radio signal emission including the commonreference signal in the effected interval. User equipment may not beaware of the loss of common reference signal without explicit signalingof this change and, as a result, may incorrectly performsynchronization/tracking and channel measurements.

User equipment, for example, can transmit autonomously data traffic orrandom access attempts on an uplink channel, e.g., an uplink channel ina cellular system. As a result, a base station or a scheduler may notcompletely control uplink transmissions. Therefore, once a system plansto switch an uplink interval to a downlink interval, the system has towait for user equipment to cease radio signal emissions in the effectedinterval. User equipment in an autonomous transmission status may stilltransmit signals in the effected interval without explicit signaling ofthe change. In addition, a base station can schedule uplinktransmissions from certain user equipment as persistent, e.g., there canbe multiple persistently scheduled user equipment transmissions in theeffected intervals. A system may require a large amount of downlinkresources to send individual scheduling information to each of theseuser equipments to stop the persistent transmissions in the effectedintervals. Thus, it may be advantageous to broadcast a single signalingmessage on a downlink to stop multiple persistent uplink transmissionsin the effected intervals.

A downlink channel such as a broadcast channel can carry explicitsignaling to inform one or more mobile devices of the location of a muteinterval(s) within a radio frame. Further, techniques for signaling amute interval can differ between implementations with different framestructures such as slot and symbol frame structures. Slot-TDD framestructure implementations, for example, can use a slot mask method, aslot list method, or a pre-defined allocation table entry (ATE) method.Whereas, symbol-TDD frame structure implementations, for example, canuse a symbol set method or a symbol list method.

FIG. 4 shows an example of mute slot signaling using a slot mask. A slotmask method can include broadcasting an N-bit mask, where N is equal tothe total number of downlink and uplink slots in a frame, along with anexisting signaling format that indicates a D/U allocation table. Thei-th binary bit, m_(i), in the mask corresponds to i-th data slot in theframe. If m_(i) is set to 1, the i-th slot in the frame is designated asa mute slot; otherwise, the i-th slot can be used for either downlink oruplink transmissions according to the accompanied D/U allocation table.An N-bit mask can include one or more bits that respectively indicateone or more slots as mute slots. Different implementations can realizedifferent slot mask method implementations. For example, a slot mask canbe separate from an allocation table in a frame. In another example, acombined data structure can represent both an allocation table and aslot mask. The combined data structure can include N entries, and eachentry can include a bit for a D/U allocation and a bit for a slot maskindication.

FIG. 5 shows an example of mute slot signaling using a slot list. A slotlist method can include broadcasting a list of one or more slot indicesalong with signaling information that indicates a D/U allocation table.In some implementations, a slot is marked as a mute slot if the slot'sindex within the frame is in a frame's slot list. If not so marked, theslot is either a downlink slot or an uplink slot according to theframe's D/U allocation table. Different implementations can realizedifferent slot list method implementations. For example, mute slots canbe adjacent to each other and can follow an uplink slot and to precede adownlink slot, and as a result, the indices in the list can be replacedby the number of muted slots. In some implements, mute slots can beinterleaved with other slot types.

A pre-defined allocation table entry method for a slot-TDD framestructure can use pre-defined formats to signal the existence andlocations of mute slots. For exampled, a pre-defined format can specifyframe patterns with mute slots. A pre-defined allocation table entrymethod can include the mute slot signaling information in one or moreextended entries of a TDD allocation table.

FIG. 6 shows an example of mute symbol signaling using a symbol set. Asymbol set method can include broadcasting a symbol set and D/Uallocation information, e.g., the number of downlink/uplink symbols. Asymbol set can specify symbol locations within a frame to mark therespective symbols as mute symbols. For example, a symbol set caninclude one or more indices of symbols in a frame to designated them asmute symbols.

In some implementations, the muted downlink symbols in a broadcastsymbol set can construct a continuous mute interval in the time domainbecause of the timing characteristics of a symbol-TDD frame structure.Further, such a continuous downlink mute interval can be adjacent to aguard period in a frame. In some implementations, the muted uplinksymbols in the broadcast symbol set can construct a continuous muteinterval in time domain. Further, such a continuous uplink mute intervalcan be adjacent to a guard period in a frame. In some implementations, abase station can broadcast the indices of mute symbols. In someimplementations, a base station can broadcast the number of mutedsymbols with a flag to indicate whether these symbols are downlink oruplink symbols. In some implementations, a base station can broadcastthe starting symbol index for a mute interval with a flag to indicatewhether this mute interval is on a downlink or an uplink.

A pre-defined allocation table entry method for a symbol-TDD framestructure can use pre-defined formats to signal the existence andlocations of mute symbols. For exampled, a pre-defined format canspecify frame patterns with mute symbols. A pre-defined allocation tableentry method can include the mute symbol signaling information in one ormore extended entries of a TDD allocation table.

During wireless communication, a frame may or may not include a muteinterval(s). Zero mute interval signaling can result in a frame withoutmute intervals. Non-zero mute interval signaling can result in a framewith mute intervals. When a frame does include a mute interval, it maybe referred to as non-zero mute interval signaling. Non-zero mutesignaling can result in different processing within a radio station suchas a base station or a mobile device. A wireless communication canoperate using procedures such as delayed-mute or immediate-muteoperating procedures. A TDD system can use delayed-mute orimmediate-mute operating procedures for non-zero mute intervalsignaling.

In a delayed-mute example, once a base station sends non-zero muteinterval signaling, the base station and mobile device(s) can nottransmit new traffic (e.g., traffic not yet scheduled at the time oftransmission of the non-zero mute interval signaling) within the muteintervals identified by non-zero mute interval signaling. However, thebase station and the mobile device(s) can continue the transmission oftraffic already scheduled at the time of transmission of non-zero muteinterval signaling within those mute intervals identified by non-zeromute interval signaling. The system should manage to complete all thetransmission of the existing traffic within those mute intervalsidentified by non-zero mute interval signaling based upon certainstrategies.

In an immediate-mute example, once a base station sends the non-zeromute interval signaling, both the base station and mobile device(s) cannot transmit in the mute intervals identified by non-zero mute intervalsignaling.

A wireless communication system can specify different operation rulesets for handling mute interval signaling. A core network can establishan operation rule set for base stations and mobile devices under thecore network's control.

In some implementations, a base station can conform to the followingoperation rule, defined as

_(BS) ^(DL), if the base station is requested to do so by a core networkto switch a downlink interval to an uplink interval. Ψ can represent theset of downlink slots or the set of downlink symbols that the corenetwork requests to transit to uplink slots or uplink symbols. Thedefinition of

_(BS) ^(DL) is as follows. A base station can reserve specific downlinkslots or downlink symbols per radio frame to broadcast the content of Ψon a per-frame basis. The base station can continue normal operationswithin the slots or symbols that are not in Ψ. The base station may notschedule new user traffic within the muted slots or symbols in Ψ. Thebase station can continue the existing downlink user traffic duringthose muted intervals in Ψ. In some implementations, the base stationcan finish the existing traffic transmission as soon as possible. Insome implementations, a local policy of the base station can handleexisting downlink user traffic. Once user traffic during the mutedintervals in Ψ has terminated, the base station can inform the corenetwork of this termination event, and can stop radio signaltransmission, including a common reference signal and common controlchannels, during these mute intervals. The base station can resume usageof muted intervals, according to a command from a core network. As aresult, the base station can broadcast this resume event to mobiledevices by, for example, transmitting new mute interval signaling orzero mute interval signaling and a D/U allocation table.

In some implementations, a user equipment can conform to the followingoperation rule, defined as

_(UE) ^(DL), upon receiving mute interval signaling to switch a downlinkinterval to an uplink interval: The definition of

_(UE) ^(DL) is as follows. Ψ can represent the set of downlink slots orthe set of downlink symbols in the mute interval signaling. Thedefinition of

_(UE) ^(DL) is as follows. For the downlink slots or downlink symbolsthat are not in non-empty Ψ, the user equipment can perform normaloperations during these slots or symbols. For the downlink slots ordownlink symbols that are in Ψ, if the user equipment has no downlinktraffic within Ψ, then the user equipment can treat the mute intervalsin Ψ as an additional guard period, and may not attempt to receiveand/or monitor a signal during these intervals. If the mute intervalsignaling is interpreted as delayed-mute, then the user equipment canmonitor, measure, and receive downlink signals within these intervalsuntil all of the user equipment's traffic utilizing these intervalscompletes. After completion, the user equipment can treat the muteintervals in Ψ as an additional guard period, and shall not attempt toreceive and/or monitor any signal during these intervals. If the muteinterval signaling is interpreted as immediate-mute, then the userequipment can immediately treat the mute intervals in Ψ as an additionalguard period, and may not attempt to receive and/or monitor a signalduring these intervals. The user equipment can resume normal operationduring the specific muted intervals after receiving a new signaling,which can be zero or non-zero mute interval signaling, along with a D/Uallocation table from the base station.

In some implementations, a base station can conform to the followingoperation rule, defined as

_(BS) ^(UL), if the base station is requested by a core network toswitch an uplink interval to a downlink interval. Ψ represents the setof uplink slots or the set of uplink symbols that the core networkrequests to transit to downlink slots or downlink symbols. Thedefinition of

_(BS) ^(UL) is as follows. The base station can reserve specificdownlink slots or downlink symbols per radio frame to broadcast thecontent of Ψ on a per-frame basis. The base station can continue normaloperations within the slots or symbols that are not in non-empty Ψ. Thebase station can stop monitoring and receiving uplink signals that anyuser equipment sends autonomously during those mute intervals in Ψ. Thebase station can continue the reception of scheduled uplink packet(s)during those muted intervals in Ψ. In some implementations, the basestation can schedule and cooperate with the user equipments to finishthe existing uplink traffic transmission during those intervals as soonas possible. In some implementations, a the local policy of the basestation and user equipment can handle existing uplink user traffic. Onceuser traffic during the muted interval in Ψ has terminated, the basestation shall can inform the core network of this event. The basestation can resume usage of muted intervals, according to the commandfrom core network. The base station can broadcast this event to serveduser equipments by for example, transmitting a new signaling, which canbe zero or non-zero mute interval signaling, along with a D/U allocationtable.

In some implementations, a user equipment can conform to the followingoperation rule, defined as

_(UE) ^(UL), upon receiving non-zero mute interval signaling to switchan uplink interval to a downlink interval. Ψ can represent the set ofuplink slots or the set of uplink symbols in the mute interval signalingThe definition of

_(UE) ^(UL) is as follows. For the uplink slots or uplink symbols thatare not in non-empty Ψ, the user equipment can perform normal operationsduring these slots or symbols. For the uplink slots or uplink symbolsthat are in Ψ, if the user equipment has no uplink traffic within Ψ,then the user equipment can treat the mute intervals in Ψ as anadditional guard period, and may not transmit a signal during theseintervals. If the mute interval signaling is interpreted asdelayed-mute, then the user equipment can stop any autonomoustransmission during these intervals, however, the user equipment cancontinue to transmit scheduled uplink packet traffic within theseinterval as in normal operation until the user equipment's user trafficutilizing these intervals completes. After completion, the userequipment can treat the mute intervals in Ψ as an additional guardperiod, and may not attempt to transmit a signal during these intervals.If the mute interval signaling is interpreted as immediate-mute, thenthe user equipment can stop immediately all of its user trafficutilizing these intervals, and can treat the mute intervals in Ψ as anadditional guard period. The user equipment can resume normal operationduring the muted intervals upon a new signaling, which can be zero ornon-zero mute interval signaling, along with a D/U allocation table fromthe base station.

In some implementations of the operation rules, a base station cangenerate a data structure to specify a location(s) of mute symbols orslot according to one of the following techniques: a slot-mask method ora slot-list method for a slot-TDD frame structure; a symbol-set methodfor a symbol-TDD frame structure; and a pre-defined allocation tableentry method for both slot-TDD and symbol-TDD frame structures.

A wireless communication system can include system functions forcreating mute intervals and recovering from the mute intervals.Different finite state machines can be used to describe the operationalbehavior of the base station (BS) and user equipment (UE). Table 1 givesan example of a finite state machine for the user equipment (UE) and forthe base station (BS) along with their associated states, descriptions,and operational rules.

TABLE 1 States and associated descriptions in CN, BS and UE StateDescriptions Operation rule UE A1 Radio frame does not include a muteinterval. UE performs N/A normal operations. A2 Radio frame does includea mute interval(s), and UE has

_(UE) ^(DL) for unfinished scheduled traffic in the mute interval(s). Inthis downlink state, UE can stop autonomous transmission and can finishand the scheduled packet traffic as soon as possible. This state

_(UE) ^(UL) for exists if mute interval signaling is interpreted asdelayed- uplink mute. A3 Radio frame does include a mute interval(s),and UE keeps all transmission and/or reception out of the muteinterval(s), and UE can stop monitoring in the mute interval. BS B1Radio frame does not include a mute interval. BS performs N/A normaloperations. B2 Radio frame does include a mute interval(s), and there is

_(BS) ^(DL) for unfinished scheduled packet traffic in the muteinterval(s). In downlink this state, BS can stop scheduling new usertraffic to finish and already-scheduled packet traffic in the muteinterval(s) as

_(BS) ^(UL) for soon as possible. For downlink during this state, BS canuplink transmit common reference signals and common control channels.This state exists if mute interval signaling is interpreted asdelayed-mute. B3 Radio frame does include a mute interval(s), and BSkeeps all transmission and/or reception out of the mute interval(s),including the transmission of common reference signals and commoncontrol channels.

A core network (CN) can request a set of base stations, represented byΩ, to shutdown specific downlink or uplink intervals defined in Ψ viamute signaling by using a mute( ) function. In some implementations, afunction to initiate one or more mute intervals, called mute(Ω, Ψ), canbe defined as follows. The core network can send a Mute Request thatcontains Ψ to all base stations in Ω through a backhaul network. Uponreception of Mute Request from core network, the base station can sendmute interval signaling containing Ψ along with D/U allocation table,and enters state B2 if mute interval signaling is interpreted asdelayed-mute or state B3 if mute interval signaling is interpreted asimmediate-mute. The delay between reception of Mute Request andtransmission of mute interval signaling is decided by base stationaccording to local strategy. Once the base station in state B2 sensesthat there is no radio signal transmitted within the muted intervals(via its scheduler), it sends a Mute Response to the core network, andenters into the state B3. The reception of the non-zero mute intervalsignaling can force the user equipment into state A2 if the muteinterval signaling is interpreted as delayed-mute, or state A3 if muteinterval signaling is interpreted as immediate-mute. Once the userequipment in state A2 has no radio transmission or reception duringthose mute intervals, the user equipment enters into state A3.

A core network (CN) can requests a set of base stations, represented byΩ, to recover one or more specific muted intervals defined in Ψ todownlink/uplink slots or symbols using a mute_recover( ) function. Insome implementations, a function to recover from one or more muteintervals, called mute_recover(Ω, Ψ), can be defined as follows. Thecore network can send a Mute_Recover Command that contains Ψ (orequivalently the new D/U allocation table) to all base stations in Ω.Upon receiving this command, the base station shall obtain the new D/Uallocation table and transmit it along with the new mute intervalsignaling that can be zero mute interval signaling. The delay betweenreception of Mute_Recover Command and transmission of new mute intervalsignaling is decided by the base station according to a local strategy.Meanwhile, the base station can treat the new D/U allocation table asthe current one, and resume the radio signal transmissions during thoseintervals that are un-muted in the new mute interval signaling. Thisbrings the base station back to state B1 if there are no more muteintervals in the radio frame. In some implementations, the base stationsends a Mute_Recover Confirmation to the core network to confirm thebase station current D/U allocation table. After receiving the new muteinterval signaling, UE returns back to state A1 if there are no moremute intervals in the radio frame. In some implementations, the creationand removal of the mute intervals are asynchronous among the basestations.

FIGS. 7A, 7B, 8A, 8B, 9A, and 9B show different processing and networkflows examples for implementations of the technologies described herein.These figures correspond to Table 1 as described above. FIGS. 7A,7B showdifferent examples of processing mute intervals in a base station. FIG.7A shows states of a finite state machine (FSM) and transitions betweenthose states using a delayed-mute technique. FIG. 7B shows states of afinite state machine (FSM) and transitions between those states using aimmediate-mute technique. FIGS. 8A,8B show different examples ofprocessing mute intervals in a mobile device such as user equipment.FIG. 8A shows states of a finite state machine (FSM) and transitionsbetween those states using a delayed-mute technique. FIG. 8B showsstates of a finite state machine (FSM) and transitions between thosestates using a immediate-mute technique. FIGS. 9A,9B show differentexamples of network flow for mute and mute recover functions. FIG. 9Ashows an example flow for delayed-mute. FIG. 9B shows an example flowfor immediate-mute.

A wireless communication system can use mute intervals and associatedoperation rules and functions for different situations. For example, thesystem can use the technologies described herein to switch from an oldD/U allocation ratio to a new D/U allocation ratio. In another example,the system can use the technologies described herein to maintain a D/Uallocation ratio of one service area differently from a D/U allocationratio of a neighboring area.

A wireless communication system can perform multiple adjustments to aD/U allocation ratio to achieve a target D/U allocation ratio. Forexample, a TDD wireless system can have a D/U allocation ratio specifiedby N_(D):N_(U), where N=N_(D)+N_(U) is the total number of data slotsper frame in slot-TDD frame structure or data symbols per frame insymbol-TDD frame structure. The TDD system needs to change to a targetD/U ratio specified by (N_(D)+N₀):(N_(U)−N₀). In other words, the systemneeds to switch N₀ uplink slots or symbols to downlink slots or symbols.The procedure of changing the D/U ratio to (N_(D)−N₀):(N_(U)+N₀) issimilar to that of changing the D/U ratio to (N_(D)+N₀):(N_(U)−N₀). Amulti-step adjustment scheme can achieve the target D/U ratio. Amulti-step adjustment scheme can increase the system's efficiency andcan provide optimal trade-off between the maximum instant loss of systemcapacity and total time spent in this D/U ratio adjustment.

In some implementations, a multi-step adjustment scheme includes thefollowing details. In a K-step D/U ratio adjustment algorithm, let

$N_{0} = {\sum\limits_{k = 1}^{K}{N_{k}.}}$The k-th step adjustment is implemented as changing the D/U ratio from(N_(D)+S_(k−1)):(N_(U)−S_(k−1)) to (N_(D)+S_(k)):(N_(U)−S_(k)), where

$S_{k} = \left\{ \begin{matrix}0 & {k = 0} \\{\sum\limits_{l = 1}^{k}N_{l}} & {k > 0.}\end{matrix} \right.$The values of N_(k) for 1≦k≦K are determined by the cellular networkoperator based upon different criteria. For example, to minimize themaximum of N_(k), the (N₀ mod K) identical integers equal to ┌N₀/K┐ and(K−(N₀ mod K)) identical integers equal to └N₀/K┘ are distributed toN_(k) for 1≦k≦K. The above description can be formulated as algorithmbelow. Given N=N_(D)+N_(U) and N₀, the core network can determineparameters K and N_(k) (1≦k≦K) for

${N_{0} = {\sum\limits_{k = 1}^{K}N_{k}}},$according to the core network own criteria. The initial D/U ratio isN_(D):N_(U).

A K-step D/U ratio adjustment algorithm can perform the followingoperations for one step in the adjustment algorithm. The algorithm caninitialize a value, k, to 1 and then increment k, after an adjustment,up to and including the Kth value. A core network can call mute(Ω, Ψ),where Ω is the all base stations in the network, and Ψ corresponds toN_(k) uplink slots in a slot-TDD frame structure or N_(k) uplink symbolsin a symbol-TDD frame structure. After the core network receives a MuteResponse from one or more base stations in the system's wirelessnetwork, (e.g., involved base stations are in state B3 and involved UEare in state A3 regarding to the mute interval in Ψ), the core networkcan call mute_recover(Ω, Ψ), with the Ω unchanged and Ψ corresponding tothe N_(k) slots or symbols assigned to downlink, to make the new D/Uallocation ratio as (N_(D)+S_(k)):(N_(U)−S_(k)), where

$S_{k} = {\sum\limits_{l = 1}^{k}{N_{l}.}}$After the Kth adjustment, the resulting D/U ratio for base stationswithin the system is (N_(D)+N₀):(N_(U)−N₀).

FIG. 10 shows an example of a single step change in a multiple step D/Uratio adjustment for a slot based frame structure. FIG. 11 shows anexample of a single step change in a multiple step D/U ratio adjustmentfor a symbol based frame structure. In these two figures, theasynchronous operations among base stations are confirmed.

In some implementations, the maximum instant system capacity loss ratioin a K-step D/U ratio adjustment is given by

$\frac{\max_{k = 1}^{K}\left\{ N_{k} \right\}}{N} \leq {\frac{N_{0}}{N}.}$A larger K value can result in a smaller maximum instant system capacityloss. Therefore, if the network operator can tolerate the time spent inthe D/U ratio adjustment, the instant system capacity loss ratio duringthe adjustment can be controlled, e.g., as small as 1/N. As a potentialbenefit, the user traffic may not be interrupted.

A wireless communication system can maintain a D/U allocation ratio ofone service area differently from a D/U allocation ratio of aneighboring area. Similar to a K-step adjustment algorithm that changesa D/U ratio from time instance A to time instance B by spreading thetotal system capacity loss over that time duration between A and B, aK-tier D/U ratio adjustment method can spread system capacity loss overdifferent base stations. A K-tier D/U ratio adjustment method canmaintain a different D/U ratio in service area A from that in servicearea B.

A wireless communication system can perform K-tier D/U ratioadjustments. A TDD wireless system can have an D/U allocation ratio asN_(D):N_(U), where N=N_(D)+N_(U) is the total number of data slots perframe in slot-TDD frame structure or data symbols per frame insymbol-TDD frame structure. The TDD system can change the D/U ratiowithin a certain area to (N_(D)+N₀):(N_(U)−N₀), that is, to switch N₀uplink slots or symbols to the downlink. The case of changing the D/Uratio to (N_(D)−N₀):(N_(U)+N₀) is similar to the case for changing theD/U ratio to (N_(D)+N₀):(N_(U)−N₀).

In some implementations, a K-tier D/U ratio adjustment algorithmincludes the following details. The area for which D/U ratio is kept thesame after an adjustment is called tier-0. The area for which the targetD/U ratio is desired after the adjustment is called tier-K. Betweentier-0 and tier-K there are K−1 tiers called tier-1, tier-2, . . . andtier-(K−1). Here, each tier is can be wide enough to isolate the radiosignals transmitted from two adjacent tiers. Let

$N_{0} = {\sum\limits_{k = 1}^{K - 1}{N_{k}.}}$The values of N_(k) for 1≦k<K are determined by the cellular networkoperator based upon different criteria. For example, to minimize themaximum of N_(k), the (N₀ mod (K−1)) identical integers with value of┌N₀/K−1┐ and (K−(N₀ mod (K−1))) identical integers with value of└N₀/K−1┘ are distributed to N_(k) for 1≦k<K. A K-tier D/U ratioadjustment method can create one or more mute intervals for the basestations in intermediate tiers but may not recover these mute intervals.At the end of a K-tier adjustment, there are N_(k) slots or symbols inthe k-th tier to be muted. These un-recovered mute intervals can serveas guard period among tiers. There can be at least one tier withun-recovered mute intervals, that is, K>1.

The K-tier D/U ratio adjustment method can include the followingoperations. Given N=N_(D)+N_(U) and N₀, the core network can determineparameters K (K>1) and N_(k)(1≦k<K) for

${N_{0} = {\sum\limits_{k = 1}^{K - 1}N_{k}}},$according to the core network's own criteria. The initial D/U ratioacross all tiers is N_(D):N_(U). The algorithm can initialize a value,k, to 1 and then increment k, after an adjustment, up to and includingthe Kth value. For each value of k, the core network can call mute(Ω,Ψ), where Ω includes all base stations in the tiers belonging to the set{l|k≦l≦K}, and Ψ corresponds to N_(k) uplink slots in slot-TDD framestructure or N_(k) uplink symbols in symbol-TDD frame structure. Afterthe core network receives Mute Response from base stations in Ω, thecore network can call function mute_recover(Ω′, Ψ), where Ω′ includesall base stations in the tiers belonging to the set {l|(k+1)≦l≦K}, and Ψcorresponds to the N_(k) slots or symbols assigned to downlink. Afterthe Kth adjustment, the resulting D/U ratio for base stations in thek-th tier is:

$\left\{ {{\begin{matrix}{N_{D}\text{:}N_{U}} & {k = 0} \\{\left( {N_{D} + S_{k - 1}} \right)\text{:}\left( {N_{U} - S_{k}} \right)} & {0 < k < K} \\{\left( {N_{D} + N_{0}} \right)\text{:}\left( {N_{U} - N_{0}} \right)} & {{k = K},}\end{matrix}{where}S_{k}} = \left\{ \begin{matrix}0 & {k = 0} \\{\sum\limits_{l = 1}^{k}N_{l}} & {k > 0.}\end{matrix} \right.} \right.$

In some implementations, the maximum instant system capacity loss ratioper tier in the K-tier D/U ratio adjustment is given by

$\frac{\max_{k = 1}^{K}\left\{ N_{k} \right\}}{N} \leq {\frac{N_{0}}{N}.}$A larger K value can result in a smaller maximum instant system capacityloss. Therefore, if the network operator can tolerate the effected areasize during the D/U ratio adjustment, the instant system capacity lossratio during the adjustment can be controlled, e.g., as small as 1/N. Asa potential benefit, the user traffic may not be interrupted.

FIG. 12 shows an example of a multi-tier layout map with different D/Uallocation ratios. The map includes different service area controlled bya core network. In this example, the whole service area initially hasidentical D/U allocation ratios. In order to increase the D/U ratio intier-3 area, a K=3 tier layout is created, and the D/U ratio isincreased tier-by-tier as moving from tier-0 towards tier-3. FIG. 13 andFIG. 14 shows the K-tier adjustment procedure for this example. FIG. 13shows an example of a K-tier D/U ratio adjustment algorithm for a slotbased frame structure. FIG. 14 shows an example of a K-tier D/U ratioadjustment algorithm for a slot based frame structure.

FIG. 15 shows an example of a wireless communication system, such as aTDD wireless communication system. System 1500 can include a network ofbase stations (BSs) 1510 for communicating with one or more mobiledevices 1505 such as subscriber stations, mobile stations, userequipment, wireless air cards, mobile phones, and other wirelessdevices. In some implementations, a mobile device can have a fixedlocation, e.g., a desktop computer with a wireless air card. A corenetwork 1515 can include one or more controllers to control one or morebase stations 1510. A controller can include processor electronics suchas a processor(s) or specialized logic. A controller's functionality canbe split into multiple components within a core network 1515.

Mobile devices 1505 can be a mobile unit or a fixed unit. A fixed unitcan be located and/or relocated anywhere within the coverage area ofsystem 100. Fixed unit wireless device can include, for example, desktopcomputers and computer servers. Mobile units can include, for example,mobile wireless phones, Personal Digital Assistants (PDAs), mobiledevices, mobile computers.

A base station 1510 in system 1500 can include a radio transceiver. Abase station 1510 can transmit signals to a mobile device 1505 viadownlink radio signals. A mobile device 1505 in system 1500 can includea radio transceiver. A mobile device 1505 can transmit signals to a basestation 1505 via uplink radio signals.

FIG. 16 shows an example of a radio station architecture. A radiostation 1605 such as a base station or a mobile device can includeprocessor electronics 1610. Processor electronics 1610 can include aprocessing unit configured to perform one or more operations ortechniques described herein. A processing unit can include one or morespecialized or general propose processors and/or specialized logic. Aradio station 1605 can include transceiver electronics 1615 to sendand/or receive wireless signals over a communication interface such asantenna 1620. Radio station 1605 can include other communicationinterfaces for transmitting and receiving data. In some implementations,a processing unit can be configured to implement some or all of thefunctionality of a transceiver.

FIG. 17A shows an example process of a mute operation on a base station.A base station can operate 1705 under time division duplexing tocommunicate with one or more mobile devices using a frame structure. Thebase station can adjust 1710 a downlink-uplink ratio to change anallocation between uplink and downlink data capacities in the framestructure. In some implementations, a core network can control the basestation to make the adjustment.

The base station can determine 1715 a mute interval based on theadjusted downlink-uplink ratio, the mute interval can include one ormore areas of the frame structure. Determining the mute interval caninclude selecting an uplink or downlink interval within the framestructure as the mute interval. In some implementations, a mute intervalcan include one or more slots in the frame structure. In someimplementations, a mute interval can include one or more symbols in theframe structure. A mute interval can include adjacent or nonadjacentareas in the frame structure.

The base station can generate 1720 mute information based on the muteinterval to identify the one or more areas of the frame structureeffected by the allocation change. The base station can transmit 1725the mute information to the one or more mobile devices. In someimplementations, a base station can transmit data including an D/Uallocation table and mute information to the one or more mobile devices.Some implementations can combine a D/U allocation table and muteinformation.

FIG. 17B shows an example process of a mute operation on a base station.A base station can control 1750 data transmission within the muteinterval, e.g., control data transmission to complete or immediatelystop. The base station can change 1755 the mute interval into an uplinkor downlink interval according to the adjusted downlink-uplink ratio. Insome implementations, a base station can monitor activity with the muteinterval, and after activity ceases, the base station can change themute interval into an uplink or downlink interval. The base station canschedule 1760 one or more data transmissions for the changed muteinterval, e.g., the new uplink or downlink interval.

FIG. 18 shows an example process of a mute operation on a mobile device.A mobile device can use 1805 time division duplexing to communicate witha base station using a frame structure and a first allocation. The framestructure can include uplink and downlink data areas. The firstallocation can include a total size of the uplink area and a total sizeof the downlink area. The mobile device 1810 can receive mutinginformation from the base station indicative of muting activity for aspecific area of the frame structure. The specific area can include oneor more slots or one or more symbols. Multiple slots in a specific areacan be adjacent or nonadjacent within a frame structure. The mutinginformation can be indicative of a second allocation that differs fromthe first allocation.

The mobile device can complete operations 1815 associated with thespecific area under the first allocation and can commence 1820operations using the second allocation. For example, a mobile stationcan complete operations, such as stopping a data transmission in thespecific area, and can commence operations using the second allocationsuch as receiving data in the specific area. In another example, amobile station can complete operations, such as receiving datatransmission in the specific area, and can commence operations using thesecond allocation such as transmitting data in the specific area.

In some implementations, a communication link between a base station anda user equipment can be established (the communication link can includea first frame of downlink intervals for the base station to transmit tothe user equipment and uplink intervals for the user equipment totransmit to the base station); and a location of a mute interval can betransmitted on a downlink interval of the first frame. The mute intervalcan replace a downlink interval or an uplink interval from a previousframe to change a downlink to uplink allocation ratio.

In some implementations, a mute interval, corresponding to a mute slotin the slot-TDD frame structure or mute symbol in the symbol-TDD framestructure, can be used to indicate a stop of all radio transmissionsduring the interval. A slot mask method can be used by the base stationto signal the mute slots to user equipments in the slot-TDD framestructure. A slot list method can be used by the base station to signalthe mute slots to user equipments in the slot-TDD frame structure. Asymbol set method can be used by the base station to signal the mutesymbols to user equipments in the symbol-TDD frame structure, where themute symbols are contiguous and the constructed mute interval isadjacent to the guard period in symbol-TDD frame structure. Thepre-defined allocation table entry method can be used by the basestation to signal to user equipment the mute slots in the slot-TDD framestructure and the mute symbols in the symbol-TDD frame structure.

In some implementations, a base station can conform to an operation ruledefined by

_(BS) ^(DL), when switching certain downlink interval to uplinkinterval. The user equipment can conform to an operation rule defined by

_(UE) ^(DL), when switching certain downlink interval to uplinkinterval. The base station can conform to an operation rule defined by

_(BS) ^(UL), when switching certain uplink interval to downlinkinterval. The user equipment can conform to an operation rule defined by

_(UE) ^(UL), when switching certain uplink interval to downlinkinterval.

In some implementations, a network function mute( ) can include anon-zero mute interval signaling from base station to user equipment.The network function mute( ) can include a Mute Request from the corenetwork to the base station, and the Mute Response from the base stationto the core network. The network function mute_recover( ) can includezero mute interval signaling from base station to user equipment. Thenetwork function mute_recover( ) can include a Mute Recover Command fromthe core network to the base station, and the optional Mute RecoverConfirmation from the base station to the core network.

In some implementations, a K-step D/U ratio adjustment algorithm can beuse to dynamically change the D/U allocation ratio in the network. TheK-tier D/U ratio adjustment algorithm can be used to maintain the D/Uallocation ratio of one area differently from that of other areas.

The described techniques can be used to dynamically change thedownlink-to-uplink allocation ratio in scenarios such as (1) the networkneeds to switch from an old D/U allocation ratio to a new value; and (2)the network needs to keep the D/U allocation ratio of one service areadifferently from the one of the neighboring area. One or more of thefollowing features may be achieved in various implementations during thedynamic change of D/U allocation ratio: eliminating synchronizedswitching operation among base stations; minimizing the instant systemcapacity loss based on the control by the network operator withoutinterrupt frame from view-point of network; minimizing or eliminatinginterrupt to the user traffic; application of the described techniquesin both slot-TDD frame structure and symbol-TDD frame structure.

The disclosed and other embodiments and the functional operationsdescribed in this patent application can be implemented in digitalelectronic circuitry, or in computer software, firmware, or hardware,including the structures disclosed in this patent application and theirstructural equivalents, or in combinations of one or more of them. Thedisclosed and other embodiments can be implemented as one or morecomputer program products, i.e., one or more modules of computer programinstructions encoded on a computer readable medium for execution by, orto control the operation of, data processing apparatus. The computerreadable medium can be a machine-readable storage device, amachine-readable storage substrate, a memory device, a composition ofmatter effecting a machine-readable propagated signal, or a combinationof one or more them. The term “data processing apparatus” encompassesall apparatus, devices, and machines for processing data, including byway of example a programmable processor, a computer, or multipleprocessors or computers. The apparatus can include, in addition tohardware, code that creates an execution environment for the computerprogram in question, e.g., code that constitutes processor firmware, aprotocol stack, a database management system, an operating system, or acombination of one or more of them. A propagated signal is anartificially generated signal, e.g., a machine-generated electrical,optical, or electromagnetic signal, that is generated to encodeinformation for transmission to suitable receiver apparatus.

A computer program (also known as a program, software, softwareapplication, script, or code) can be written in any form of programminglanguage, including compiled or interpreted languages, and it can bedeployed in any form, including as a stand alone program or as a module,component, subroutine, or other unit suitable for use in a computingenvironment. A computer program does not necessarily correspond to afile in a file system. A program can be stored in a portion of a filethat holds other programs or data (e.g., one or more scripts stored in amarkup language document), in a single file dedicated to the program inquestion, or in multiple coordinated files (e.g., files that store oneor more modules, sub programs, or portions of code). A computer programcan be deployed to be executed on one computer or on multiple computersthat are located at one site or distributed across multiple sites andinterconnected by a communication network.

The processes and logic flows described in this patent application canbe performed by one or more programmable processors executing one ormore computer programs to perform functions by operating on input dataand generating output. The processes and logic flows can also beperformed by, and apparatus can also be implemented as, special purposelogic circuitry, e.g., an FPGA (field programmable gate array) or anASIC (application specific integrated circuit).

Processors suitable for the execution of a computer program include, byway of example, both general and special purpose microprocessors, andany one or more processors of any kind of digital computer. Generally, aprocessor will receive instructions and data from a read only memory ora random access memory or both. The essential elements of a computer area processor for performing instructions and one or more memory devicesfor storing instructions and data. Generally, a computer will alsoinclude, or be operatively coupled to receive data from or transfer datato, or both, one or more mass storage devices for storing data, e.g.,magnetic, magneto optical disks, or optical disks. However, a computerneed not have such devices. Computer readable media suitable for storingcomputer program instructions and data include all forms of non volatilememory, media and memory devices, including by way of examplesemiconductor memory devices, e.g., EPROM, EEPROM, and flash memorydevices; magnetic disks, e.g., internal hard disks or removable disks;magneto optical disks; and CD ROM and DVD-ROM disks. The processor andthe memory can be supplemented by, or incorporated in, special purposelogic circuitry.

While this specification contains many specifics, these should not beconstrued as limitations on the scope of an invention that is claimed orof what may be claimed, but rather as descriptions of features specificto particular embodiments. Certain features that are described in thisspecification in the context of separate embodiments can also beimplemented in combination in a single embodiment. Conversely, variousfeatures that are described in the context of a single embodiment canalso be implemented in multiple embodiments separately or in anysuitable sub-combination. Moreover, although features may be describedabove as acting in certain combinations and even initially claimed assuch, one or more features from a claimed combination can in some casesbe excised from the combination, and the claimed combination may bedirected to a sub-combination or a variation of a sub-combination.Similarly, while operations are depicted in the drawings in a particularorder, this should not be understood as requiring that such operationsbe performed in the particular order shown or in sequential order, orthat all illustrated operations be performed, to achieve desirableresults.

Only a few examples and implementations are disclosed. Variations,modifications and enhancements to the described examples andimplementations and other implementations may be made based on what isdisclosed. For example, some wireless systems may have differentterminologies for aspects discussed above. For example, a slot can benamed or can include a subframe or a frame in some wireless system.Further, in some wireless systems where a slot includes a frame, asuperframe can include multiple such slots. Different TDD systems mayhave different protocol interpretations for the technologies describedherein.

1. A method for dynamically changing a downlink-uplink allocation,comprising: establishing a communication link between a base station anda user equipment, wherein the communication link comprises downlinkintervals for the base station to transmit to the user equipment anduplink intervals for the user equipment to transmit to the base station;and generating a mute interval to replace a downlink interval or anuplink interval in a previous flame to effect a change in adownlink-uplink allocation ratio for a subsequent frame, the muteinterval indicating that transmissions during the mute interval shouldcease; and transmitting a location of the mute interval to the userequipment using a frame structure; operating a core network to send amute request to the base station to initiate the change in thedownlink-uplink allocation ratio; operating the base station to send amute response to the core network; and operating the core network tosend a mute recovery request to the base station.
 2. The method of claim1, wherein the frame structure includes a slot-TDD frame structure,wherein the mute interval corresponds to one or more slots within thesubsequent frame.
 3. The method of claim 1, wherein the frame structureincludes a symbol-TDD frame structure, wherein the mute intervalcorresponds to one or more mute symbols within the subsequent frame, andthe mute interval indicates that transmissions during the mute intervalshould cease.
 4. The method of claim 3, wherein the mute symbols arecontiguous and the mute interval is adjacent to a guard period withinthe subsequent frame.
 5. The method of claim 1, further comprising:generating a data structure to specify the location of the muteinterval, wherein the data structure is one of a bit mask datastructure, a list data structure, a symbol set data structure, or apre-defined allocation table entry structure, wherein transmitting thelocation comprises transmitting the data structure.
 6. The method ofclaim 1, wherein generating the mute interval comprises generatinginformation to indicate a presence of a mute slot in a specific slot ofthe frame structure, wherein the mute interval comprises the mute slot.7. The method of claim 6, further comprising: changing a downlink slotin the frame structure to the mute slot; and operating the base stationto either complete or immediately stop data transmission in the muteslot.
 8. The method of claim 7, further comprising: changing the muteslot to an uplink slot; and controlling the user equipment to transmitin the uplink slot.
 9. The method of claim 6, further comprising:changing an uplink slot in the frame structure to the mute slot; andoperating the user equipment to either complete or immediately stop datatransmission in the mute slot.
 10. The method of claim 9, furthercomprising: changing the mute slot to a downlink slot; and operating thebase station to transmit in the downlink slot.
 11. The method of claim1, wherein generating the mute interval comprises generating informationto indicate a presence of a mute symbol in a specific symbol of theframe structure, wherein the mute interval comprises the mute symbol.12. The method of claim 11, further comprising: changing a downlinksymbol in the frame structure to the mute symbol; and operating the basestation to either complete or immediately stop data transmission in themute symbol.
 13. The method of claim 12, further comprising: changingthe mute symbol to an uplink symbol; and controlling the user equipmentto transmit in the uplink symbol.
 14. The method of claim 11, furthercomprising: changing an uplink symbol in the frame structure to the mutesymbol; and operating the user equipment to either complete orimmediately stop data transmission in the mute symbol.
 15. The method ofclaim 14, further comprising: changing the mute symbol to a downlinksymbol; and operating the base station to transmit in the downlinksymbol.
 16. The method of claim 1, wherein generating the mute intervalcomprises generating a bit-mask data structure to identify one or moreslots in the frame structure effected by a muting operation.
 17. Themethod of claim 1, wherein generating the mute interval comprisesgenerating a list data structure to identify one or more slots of theframe structure effected by a muting operation.
 18. The method of claim1, wherein generating the mute interval comprises generating a set datastructure to identify one or more symbols of the frame structureeffected by a muting operation.
 19. The method of claim 1, whereingenerating the mute interval comprises generating one or morepre-defined allocation table entries to identify one or more areas ofthe frame structure effected by a muting operation.
 20. The method inclaim 1, wherein the mute request includes the information indicative ofspecific intervals to be muted in the frame structure.
 21. The method inclaim 20, wherein the mute request includes one of the following datastructures defining one or more specific intervals in the framestructure: a bit mask data structure, a list data structure, a set datastructure, and pre-defined allocation table entries.
 22. The method inclaim 1, wherein the mute response is sent from the base station afterthe base station has no communication activities in the mute interval.23. The method in claim 1, wherein the mute recovery request includesinformation indicative of a specific current mute interval of the framestructure that is to be changed to either a downlink interval or anuplink interval.
 24. The method in claim 23, wherein the mute recoveryrequest includes one of the following data structures defining specificintervals in the frame structure: a bit mask data structure, a list datastructure, a set data structure and pre-defined allocation tableentries.
 25. The method in claim 1, further comprising: operating thebase station to send a mute recovery confirmation to the core network,wherein the mute recovery confirmation is sent from base station afterthe base station resumes usage of the specific mute intervals of theframe structure for either uplink or downlink transmissions.